1. Field of the Invention
The invention concerns a method to determine a parameter of a fixing element for an implant to be affixed to a bone.
2. Description of the Prior Art
Implants, for example nails and plates for fixing bones having a fracture, are used in traumatology. These implants are attached to the bone with the use of fixing elements, for example screws. For optimal attachment, these must be introduced into the body of a patient in an optimally advantageous attitude, thus in a correct position and at a correct angle. In addition to these parameters, the correct length of the fixing element also plays an important role for achieving the correct purchase (hold).
These parameters of the fixing elements have conventionally been selected corresponding to the prior clinical and anatomical knowledge of the surgeon. For example, using x-ray exposures, the surgeon decides where and how a suitable fixing element must be introduced into the body of the patient, which then occurs with x-ray monitoring. Errors can therefore occur both in the manual selection of the parameters and in the introduction of the fixing element. If the length of the fixing element is chosen too short, a sufficient purchase for the implant cannot be assured. By contrast, if the length is chosen too long, the fixing element may project from the bone and protrude into tissue surrounding the bone, or into a joint space, such that significant injuries can arise. Moreover, it is possible that the fixing elements may be inserted at an incorrect attitude (for example at a disadvantageous angle) into the bone, so an optimal stability of the implant at the bone is not ensured.